Liquid rheostat



Patented May 18, 1920.

2 SHEETS-SHEET 1.

A. J. NICHT,JR.

LIQUID RHEOSTAT.

APPLICATION FILED. FEB. 1.1.. 1.916.

Patented May 18,1920.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

ALEXANDER J. NIGHT, JR, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-'CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A

CORPORATION OF DELAWARE.

LIQUID RHEOSTAT.

Original application filed January To all whom it may concern:

Be it known that I, ALEXANDER J. N orrr, Jr. a citizen of the UnitedStateS, IeS1d1I1g at Milwaukee, in the county of Milwaukee and State of\Visconsin, have invented a certain new and useful Improvement in LiquidRheostats, of which the following is a specification.

This invention relates in general to liqu d rheostats such as aregenerally useful in controlling the resistance of electrical clrcuits,and are of particular utility in controlling the operation of electricmotors.

The present application is a (llVlSlOIl of application Serial No.815,341, filed January 30, 1914, the latter appllca-tlon describing asystem .of hoist control embodying a rheostat of the type which formsthe subject matter of the present application.

It is an object of this invention to provide a liquid rheostat ofimproved construction.

It is a further object of this invention to provide a liquid rheostat of1mroved construction wherein electrolyte 1s circulated through areservoir compartment and an electrode-containing compartment, andwherein improved means are provided for controlling the immersion of theelectrodes in the electrolyte.

These and other objects are attained by this invention, the variousnovel features of which will appear from the description and drawings,disclosing one embodiment of such invention, and will be particularlypointed out in the claims.

Figure 1 is a View in elevation, partly in section, of a rheostat andapparatus for controlling the same embodying features of this invention,the rheostat being shown as being connected in the secondary circuit ofa polyphase induction motor. I

Fig. 2 is a view similar to Fig. 1, showing a modified form of thisinvention.

Fig. 3 is a fragmentary elevational view, showing an automaticallyoperated valve and latch means therefor, forming a detail of theapparatus shown in Figs. 1 and 2.

Fig. 4 is a view in elevation of a movable weir or gate forming a partof the rheostat shown in Fig. 2.

Specification of Letters Patent.

30, 1914, Serial No. 815,841. ruary 11, 1916. Serial No. 78,047.

Fig. 5 represents a fragmentary Section on the line V-V of Fig. 2, butwith the weir or gate in its upper position.

In the embodiment of the invention disclosed, the rheostat is of thepolyphase type, such as ma be useful forjcontrolling the resistance 0the secondary circuit of a polyphase, wound-rotor induction motor, heredesignated as M, and comprises a casing 30 divided by the partition 31,into two compartments 32 and 33. It is obvious that, instead ofproviding a single casing divided into a plurality of compartments, twoseparate casings might be used. The upper compartment or casing 32 isdesigned to con-' tain electrodes 34, 35, 36, in series with thepolyphase circuit, as for instance, the secondary circuit of a motor.These electrodes may be of any suitable form, but each preferablyconsists of one or more metal plates spaced apart and rigidly secured inposition. These electrodes are immersed in a body of resistance-liquid,preferably slightly acidulated water.

The lower compartment 33 of the casing 30 acts as a reservoir for liquidresistance material. A pump 37 driven by a motor 38, or any othersuitable means, acts to force the resistance-fluid through the pipe 39to the upper compartment 32.

It is obvious that the'resistance in the circuit to be controlled variesinversely as the amount of resistance-fluid in contact with theelectrodes in the upper compartment. For varying the amount of suchfluid and thus varying the resistance, one or more movable weirs 40,passing through the partition 31, are provided, which act as overflowpassages to discharge fluid from the upper compartment to the lowersupply compartment, the weirs being adjustable through the partition 31to vary the level at which the resistance-fluid in the compartment 32overflows, and, in their lowermost position, maintaining such a level offluid that the electrodes are slightly immersed.

During the normal operation of a motor to be controlled, it is desirablethat the pump 37 be continually operated to circulate the resistancefluid between the lower and upper compartments. The rate at which thiscirculation takes place may be varied by adjustin the valve 41, hereshown asof the butter y type, in the communicating passage 39 ;With suchsystem as is here described, fluid that becomes heated through use as aresistance element in the upper compartment 32 asses off at its upperlevel and is discha'r ed into the lower compartment 33. The owercompartment may be provided with a plurality of cooling pipes 42 throughwhich air or other cooling fluid may circulate to assist in cooling theliquid in this compartment. The weirs 40 are operated by a pivoted lever43, through a rod 44 connected to an operating member.

When the motor to be controlled is not in operation, only the lower endsof the electrodes'34, 35, 36, are immersed in the fluid resistance, thelevel of the fluid being lowest and the overflow weirs 40 being at theirlowest point. With this condition existing, the resistance of thesecondary circuit of the motor is a maximum. When the motor is startedthe weirs are lifted to their upper level and the pump 37 forces liquidinto the compartment 32, gradually filling the same and decreasing theresistance inthe circuit, that is, the secondary of the motor, unt1l thelevel reaches the weir outlet, when the secondary is practicallyshort-circuited. The motor then operates at its maximum speed. To stopthe motor, resistance is first inserted in the secondary circuit bymoving the weirs to their lower level and allowing the liquid todischarge to the lower compartment. When the liquid is at its lowerlevel, the switch in the primary circuit of the motor may be opened,and, as little current is flowing therein, practically no arcingresults.

In order to insure safe operation of a motor with which the rheostat isassociated, and generally to incorporate in the apparatus an auxiliarycontrolling'device for the rheostat, means are provided for causing thedischarge of fluid resistance from the upper compartment 32,independently of the weirs 40. This means comprises a by-pass 61, shownalso in Fig. 3, between the compartments, the passage through which isnormally obstructedby a valve 62, biased to open position by a weightedlever 63 and normally held 'closed by a latch 64, engaging a projection65 on an operating handle 66 of the valve. The latch 64 is normallymaintained in engagement with the projection 65, to hold the valve 62 inclosed position, by an electromagnet 67, the latch 64 being mounted onthe armature of said magnet. An adjustable stop 68 engages the handle 66when the valve is open to limit the size of the discharge passagethrough the pipe This by-pass outlet 61 may be so disposed as to emptythe upper compartment to any desirable extent, depending on what vm-aybe changed to anything desirable by providing the inlet to the by-passwith an extension that will permit emptying the tank to only the desiredlevel.

Under normal conditions, as while the operation of the motor controlledb the rheostat is normal, the circuit of the atchholding magnet 67 ismaintained closed in any sultable manner; and on the occurrence of anypredetermined condition, as overload or when the load driven by themotor attains a desired condition, this circuit is opened, or the magnetis otherwise rendered ineffective to hold the. latch 64 in attractedposition, thus tripping the latch and allowing the weighted lever 63 'toopen the valve 62. Opening of this valve allows the discharge ofelectrolyte from the upper compartment and thus causes the insertion ofresistance into the secondary circuit of the motor, slowing down thesame. run at a gradually decreasing speed until the lower level isreached, at which liquid runs off through the by-pass 61. The motor maybe allowed to run with resistance in the secondary circuit or it may becut out by opening the primary switch.

' In order to hasten the insertion of resistance in the secondarycircuit of the motor, as when the by-pass valve 62 is opened, the pumpmotor 38 may be caused to stop by breaking its circuit. A switch may beprovided on the shaft of the valve 62, or arranged in any manner, toopen when the valve opens. As shown in Fig. 1, a drum 131, havingbridging contacts 132 and 133, is adapted to close two sides of athreephase pump-motor circuit by suitably bridging terminals of thiscircuit.

This switch may be operated by a chain, belt or gearing connectionbetween the shaft of valve 62 and the spindle 134 of the switch, theconnections being such as to render the pump 37 inactive when the valve62 is open.

In Fig. 2, there is disclosed a modification of the rheostat shown inFig. 1, the construction being such as better adapts the rheostat forquick insertion of resistance in the circuit to be controlled. Themodified rheostat comprises a casing 130, divided by a tray-likepartition 231, into upper and lower compartments 32 and 33,respectively.

The tray 231 is secured to the casing at three sides and the uppercompartment is formed by the tray and the side walls of the casing andis closed at the fourth side by a movable partition or weir 90, which isseparated from the fourth side of the casing, the general arrangement ofthe parts being such that the space between the fourth side of thecasing and the movable partition or well 90 serves as 'an overflowpassage to carry The motor will liquid from the upper to the lowercompartment. This weir or gate is provided w th rollers 91, see Fig. 5,operatlng m guide ways 92, 93, secured to opposite sides of the age fromthe up or compartment, while the -'we1r is in any 0 its operativepositions.

Theweir or gate .90 1s secured to a pivoted lever 94 to be operatedthereby. Thls lever 94 is operated, through a rod 95, to raise the weiror gate 90, allowing the liquid that is forced into the uppercompartment through the pipe 39, by the pump 37, to accumulate and thusreduce the secondary resistance of the motor and permit the same to pickup in speed.

The depth of the tray 23l is such that there is an appreciable amount ofliquid retained in the tray and in contact with the lower ends of theelectrodes 34, 35, 36, which project into the tray and always dip intothe liquid contained therein. This construction also maintains thesecondary circuit of the motor in closed condition, although theresistance of this circuit is quite high, when the weir 90 is lowered sothat the only resistance liquid in, the upper compartment is containedin the tray, as at starting.

This type of resistance device may be provided with the same automaticdischarge as is shown in connection with the resistance deviceillustrated in Fig. 1, in which a bypass 61 is provided with a valve 62,normally held closed by a latch 64 controlled by a novoltage magnet 67;and a switch, in the form of a drum 131, having bridging contacts 132and 133 adapted to close two sides of a three-phase pump motorcircuit,may be providedto openthe circuit of the pump motor when thevalve 62 is opened. The drum 131 may be operated by a chain, belt orweir connection between the shaft of the valve 32 and the spindle 134 ofthe drum.

It will be apparent that, in case other than electrical means are usedfor driving the pump motor, suitable cut-ofi' means may be provided tooperate in response to movement of the valve 62.

While the means for causing the slowing down of the motor underpredetermined conditions, that is, independently of the operation of theweir or weirs at the will of the operator, is described as comprising aseparate outlet from the upper compartment,

nevertheless, any apparatus capable of providing for the filling andemptying of this compartment in response to one type of control and ofproviding for the emptying of such compartment in response to theoperation of a separate control effective under predeterminedconditions, would accomplish the desired results; and, accordingly is tobe considered as within the scope of this invention.

It should be understood that it is not desired that the inventionclaimed be limited to the exact details of construction shown anddescribed, for obvious modifications will occur to a person skilled inthe art.

It is claimed and desired to secure by Letters Patent I 1. A liquidrheostat comprising a casing, electrodes adapted to be immersed inliquid in said casing, manually operable means for varying the degree ofimmersion of said electrodes, and electromagnetically operative meansfor varying the degree of immersion of said electrodes.

2. A liquid rheostat comprising an electrode-containing compartment,means for discharging liquid resistance material into said compartment,means for controllin the discharge of liquid resistance material roinsaid compartment, and additional means for controlling the discharge ofliquid resistance material from said compartment, said latter meanscomprising a controlling valve, means for holding said valve latched inclosed position, and electromagnetically actuated means forcontrollingthe operation of said valve.

3. A liquid rheostat comprising an electrode-containing compartment, apump for forcing liquid resistance material into said compartment, meansfor controllin the discharge of said resistance material rom saidcompartment, and means operatively associated withsaid last mentionedmeans for controlling said pump.

4. A liquid rheostat comprising an electrode-containing compartment, apump for forcing liquid resistance material into said compartment, amotor for driving said pump, means for controlling the discharge ofresistance material from said compartment, and means operativelyassociated with said. last mentioned means for controlling the operationof said pump driving motor.

5. A liquid rheostat comprising an electrode-containing compartment, areservoir compartment, a pump for forcing liquid resistance materialfrom said'reservoir compartment to said electrode-containingcompartment, means for controlling the discharge of resistance materialfrom said electrode-containing compartment to said resercontrollingmeans as efi'ects an increase'in the discharge from saidelectrode-containing compartment.

G. A liquid rheostat comprising a casing, a partition dividing saidcasing into a pillrality of compartments one above a portion of another,said partition being spaced from a portion of the wall of said casing, aportion of that side of the upper compart-' ment adjacent the latterportion of the easing wall being in the form of a gate movable toconstitute an adjustable overflow from said latter compartment to theother compartment.

7. A liquid rheostat comprising a casing, a partition dividing saidcasing into a p'lu rality of compartments one above another, saidpartition being spaced from the wall of said casing at one point, thatside of the upper compartment adjacent the latter portion of the casingwall being provided with an adjustable gate constituting a weirpermitting liquid to overflow from said upper compartment at differentlevels and to be discharged directly into the lower compartment.

8. A liquid rheostat comprising a casing, a partition in the form of acomparatively shallow tray dividing said casing into a pluralityofcompartments one above another, said partition being spaced from thewall of said casing at one point, a movable gate associated with saidtray at said latter point and constituting an adjustable weir for thecompartment formed at the upper side of said tray.

9. A liquid rheostat comprising a casing, means within said casingforming a compartment separate from the body portion of the casing,electrodes immersible in liquid resistance material within saidcompartment, a portion of the wall of said compartment being in the formof a gate adjustable to control the discharge of liquid resistancematerial from said compartment.

10. A liquid rheostat comprising an electrode-con-taining compartment,means for supplying liquid resistance material to said compartment, andinstrumentalities for varying the degree of immersion of the electrodesin said compartment and including an adjustable weir operative tomaintain the level of said liquid resistance material and permitoverflow thereof at different points, and electromagnetically operablemeans effective to cause a lowering of the level of the liquidresistance material in said compartment independently of the position ofsaid adjustable overflow weir.

11. A liquid rheostat comprising an electrode-containing compartment,and instrumentalities for circulating liquid resistance material throughsaid compartment and maintaining the level of said liquid resistancematerial at different points therein during such circulation, andautomatically actuatable means other than said aforesaidinstrumentalities for controlling the discharge of liquid resistancematerial from said compartment.

12. A liquid rheostat comprising an electrode-containing compartment,means for supplying liquid resistance material to said compartment,means for controlling the discharge of said liquid resistance materialfrom said compartment, and means operatively associated with said lastmentioned means for controlling the supply of resistance material tosaid compartment.

13. A liquid rheostat comprising an electrode-containing compartment anda reservoir compartment, means for supplying liquid resistance materialfrom said reservoir compartment to said electrode-containingcompartment, means for controlling such supply of'liquid resistancematerial, a communicating. passageway being provided between saidcompartments by said means and permitting the discharge of liquidresistance material from said electrode-containing compartment to saidreservoir compartment, and means for controlling such dischargecompartment, said supply-controlling means and saiddischarge-controlling means being operatively associated for dependentoperation whereby when said discharge-controlling means is actuated topermit discharge from said electrode-containingfrom saidelectrode-containing compartment the supply of liquid resistancematerial is substantially decreased.

14. In a liquid rheostat comprising an electrode-containing receptacle,means for controlling the degree of immersion of said electrodes, andelectro-responsively actuatable means having control over the degree ofimmersion superior to said first named controlling means effective tocause a change in the degree of immersion of said electrodesindependently of said first named controlling means.

15. A liquid rheostat comprising an electrode-containing receptacle,means for su plying liquid resistance material to said receptacle, andinstrumentalities for varying the degree of immersion of the electrodesin said receptacle and including an adjustable weir operative tomaintain the level of said liquid resistance material at desired pointsand permit overflow thereof, and electro-responsively actuatable meanseffective to cause a lowering of the level of the liquid resistancematerial in said rece tacle independently of the position of saidadjustable Weir.

16. A liquid rheostat comprising at least two receptacles one of whichis disposed to a desired extent within the other and has one side wallthereof spaced from a side wall of the other receptacle, said firstnamed side wall constituting a weir over which liquid resistancematerial may discharge from one receptacle to the other, and means forvarying the liquid level in said weirincluding receptacle.

17. A liquid rheostat comprising an upper electrode-containingreceptacle and a lower reservoir receptacle. said receptacles having anumber of walls in common, one of the side walls of said upperreceptacle being spaced from a side wall of said lower receptacle, saidfirst named side wall constituting a weir over which liquid resistancematerial may discharge from the upper to the lower receptacle and meansfor varying the liquid level in said upper receptacle.

18. A liquid rheostat comprising an upper electrode-containingreceptacle, a lower reservoir receptacle, said receptacles having anumber of walls in common, one of the said walls of said upperreceptacle being spaced from a side wall of said lower receptacle, saidfirst mentioned side wall c0n stituting a weir over which liquidresistance material may discharge, and means for causing a circulationof liquid resistance ma terial' between said upper and lowercompartments. I

19. A liquid rheostat comprising a casing, a partition dividing saidcasing into a plurality of compartments a portion of one above a portionof another, said partition being spaced from a portion of the wall-ofsaid casing, a portion of that side of the upper compartment adjacentthe latter portion of the casing wall constituting a weir over whichliquid resistance material may flow from said latter compartment to theother compartment.

20. A liquid rheostat comprising a casing, a partition dividing saidcasing into a plurality of compartments one above another,

said partition being spaced from the wall of said casing at one point,that side of the upper compartment adjacent the latter portion of thecasing wall constituting a weir permitting liquid to overflow from saidupper compartment and to be discharged directly into the lowercompartment.

21. A liquid rheostat comprising a casing, a partition in the form of acomparatively shallow tray dividing said casing into a plurality ofcompartments one above another, said partition being spaced from thewall of said casing at one point, a wall associated with said tray atsaid latter point and constituting a weir for the compartment formed atthe upper side of said tray.

22. A liquid rheostat comprising a casing, means Within said casingforming a compartment separate from the body portion of thecasing,electrodes innnersible in liquid resistance material within saidcompartment, a portion of the wall of said compartment constituting a.weir over which liquid resistance material may discharge from saidcompartment.

In testimony whereof the signature of the inventor is afiixed hereto.

ALEXANDER J. NIGHT, JR.

